Concave lenses are used mainly for people who are farsighted, for binoculars and for telescopes. A lens that is convave makes everything look smaller. You can fit more into the view by using a convave lens. This one is concave on both sides, or rather a double concave lens with ground edges. These are also used in classrooms for hands-on instruction in many technical subjects.

Lens is 2-3/4 inches in diameter, or 3-14 inches including the frames (color of frame may vary)

Makes objects look smaller because of it's concave lens - weighs 4.9 ounces

Many visual applications - used in classrooms as a teaching device

Comes with 16-inch nylon lanyard for you to wear around the neck

Comes with rubber frame with indented area to hold with your thumb and finger